Enzymatic breakdown of hydroxyanthranilate, a potential bladder-carcinogen by hydroxyanthranilate oxygenase will be studied, in control and pyridoxine-deficient mice, in mice of various age groups, in different tissues of mice, and in livers of different animals. Mutagenicity of tryptophan metabolites such as kynurenine, hydroxykynurenine, hydroxyanthranilate, kynurenic acid, as well as xanthurenic acid, will be studied using a mutant strain of bacterial tester. Role of noncompetitive inhibitors of hydroxyanthranilate oxygenase such as salicylic acid, and para aminobenzoic acid, on the metabolism of hydroxyanthranilate will be explored.